An Australian Journalist was arrested and his newsroom raided during a police investigation over alleged child pornography crimes.

A Current Affair reporter Ben McCormack was arrested at his home on Thursday morning and a computer was seized during the raid on Nine Network's Sydney headquarters.

The network said the allegations aren't related to any story on the program, but relate to the man's personal life.

McCormack has not yet been charged but "police have indicated charges may follow later today", 9 News reported.

Staff were made to leave the office while New South Wales police investigated.

"We are co-operating with the police. However, we are not in a position to comment any further as this is an ongoing investigation," Darren Wick, director of news and current affairs at Nine, told staff in an email.